This invention relates generally to valves and more particularly to valves which regulate flow through two conduits at the same time. The two conduits are typically an inlet and an outlet conduit of a pump.
In high pressure pump (intensifier) applications, it is desired to limit the inlet and outlet flow of working fluid to and from the pump as the operation of the pump is altered. As the pump is shut off, it is desired to limit working fluid pressure applied to the pump wherein the working fluid will not leak into, or cause pressure damage to, the integral workings of the pump. It is desired to have a normally closed blocking valve to perform the function of shutting off the inlet valve as soon as the pump shuts down.
It is also desired to reduce the outlet pressure of the high pressure pump when the pump ceases operation. A separate bleed valve is typically applied to a t-portion of the outlet conduit, and is open to bleed the outlet conduit pressure as soon as the pump ceases operation. This bleed valve is distinct from the block valve.
The block valve and the bleed valve are typically solenoid operated; solenoid controlled and fluid operated; or fluid operated. The control signal to the valve may be electric or fluidic and is provided by the pump system. If either the electric or fluidic systems operating the valve fails, then the pump will not operated correctly. This situation can result in damage to the pump, valves, or interfacing system.
It is also possible that the signals from the pump that the block or bleed valve receives be incorrect while the other signal will be correct. This possible incorrect positioning of one of the valves is also highly undesirable. These block valves and bleed valves are relatively complex and expensive to construct and maintain. It would be highly desirable to produce a unitary block and bleed valve which is simple in construction and maintenance, and where both the block and the bleed portion of the valve are forced to operate in concert.
The foregoing illustrates limitations known to exist in present valve construction for pumps. It is apparent that it would be advantageous to provide an alternate directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternate is provided including features more fully disclosed hereinafter.